Production of Zeolite-4A with Bauxite as Basic Input Material

Hi Friends,

In earlier post, we have already discussed about specifications, applications and market potential of zeolite in the World. In present post, we will discuss on a very interesting topic to assess the techno-economic viability for setting up Zeolite-4A production plant using Bauxite as the basic input material. We know that Zeolite-4A is the hydrated sodium alumino silicate having chemical formulae as Na₁₂(AlO₂)₁₂(SiO₂)₁₂.27H₂O. It is mainly used in formulation of detergents along with other, Zeolite-4A is produced using hydrated alumina and sodium silicate as key feed stocks, caustic minor applications.

Generally soda as solvent for dissolution, KCl as cation and organic amine as crystal template. In the process, hydrated alumina is dissolved in caustic soda forming sodium aluminate which is mixed in desired proportion with sodium silicate resulting in formation of silica-alumina gel. Slow crystallization of silica-alumina gel in presence of alkali and organic amine results in production of Zeolite-4A crystals by nucleation technique. The crystallized Zeolite-4A is filtered and dried to produce Zeolite-4A powder for despatch to desired destinations. In this process, the capital investment for the plant is low but manufacture cost of zeolite-4A is high because of high landed cost of hydrated alumina.

The alternative economic process route is based on Bauxite as basic input material in place of Hydrated alumina. This additional facilities in the upstream of the process will generate required volume of saturated sodium aluminate with Al2O3 content at about 120 gpl and added sodium silicate concentration to about 1.2 gram per litre. The process flow sheet can easily be developed for processing the bauxite for manufacture of zeolite-4A.The proposed plant will require the following equipment and facilities-

1. Bauxite grinder,
2. Reaction vessels,
3. Flash tanks and heat exchangers,
4. Liquor decanter and residue washers,
5. Vacuum drum filter,
6. Residue storage,
7. Steam raising Boiler,
8. Pumps, pipelines and valves,
9. Instrumentation and controls,
10. Laboratory facilities,
11. Storage tanks and vessels,
12. Mixing tanks with agitators,
13. Ageing tanks,
14. Evaporation unit,
15. Product filter,
16. Dryer,
17. Bagging machine,
18. Product storage shed.

The above item list clearly reveals that the capital investment for the proposed plant will be higher compared to conventional process route but it will attribute in reducing the manufacture cost of zeolite-4A drastically because of the availability of sodium aluminate solution at lower cost and lower requirement of sodium silicate. The sizing calculations for plant, equipment and facilities can be carried out based on the bauxite quality and required production capacity of the plant. As such, it is evident that Bauxite based zeolite-4A plant should be highly profitable, however, it is always advisable to work out the economics based on the estimated capex, opex and selling price of zeolite-4A before going ahead with execution of the plant. The selling price of synthetic zeolite-4A in  international market is US$480 to US$500 per tonne.

Hope, adequate information has been presented on the subject. Please put your views / suggestions / remarks / comments, if any.

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Thanks and regards.

Kunwar Rajendra